PSA systems were firstly implemented for the purification of hydrogen. Since its commercialization, however, this type of process has reached greater industrial importance and better economic adaptation, becoming the object of purification of different substances, such as, for instance, in the production of anhydrous alcohol, in obtaining oxygen for hospital use, in the production of nitrogen with low impurity content, among others.
The following documents are herein described as prior-art references with regard to pressure swing adsorption (PSA) processes:
U.S. Pat. No. 4,407,662 discloses a process for removing water from hydrated ethanol, comprising the steps of heating the ethanol/water mixture until it is a vapor with sufficient superheat to maintain the vapor phase and prevent substantial capillary adsorption, as the mixture passes through a dessicant bed of molecular sieves; passing the superheated ethanol/water mixture through the bed to remove sufficient water in order to increase the ethanol content in the mixture; passing a portion of the dehydrated ethanol through a second dessicant bed of molecular sieves at less than atmospheric pressure to desorb the water and ethanol on the dessicant bed from a previous dehydration cycle, and reversing the flow through the two beds, after the temperature of the first bed increases.
Patent FR 2719039 A1 discloses a process for dehydration of a water/ethanol mixture by adsorption/regeneration on a molecular sieve, comprising the steps of vaporizing and superheating the mixture; passing the mixture in the vapor state over a molecular sieve to cause adsorption of water into the molecular sieve; and concurrently and/or alternately effecting regeneration by subjecting part of the dehydrated ethanol to a supplementary stage of superheating and passing it at a pressure below atmospheric pressure over a molecular sieve that is saturated with water to desorb the adsorbed water.
U.S. Pat. No. 5,753,010 discloses a method for increasing product recovery or reducing the size of pressure swing adsorption systems (PSA) utilized for hydrogen production.
U.S. Pat. No. 5,961,694 discloses a system for the separation of a gas mixture by pressure swing adsorption (PSA) comprising one adsorber and a first vessel which can be selectively connected to the adsorber in order to temporarily store the gas which is extracted from the adsorber and reintroduced into it during a cycle.
U.S. Pat. No. 6,156,101 discloses a PSA process that utilizes a combination of cyclic feed, evacuation, purge, and repressurization steps to provide a final gas product enriched in one of the feed components.
U.S. Pat. No. 6,340,382 B1 discloses a PSA process of adsorbing substantially all of the nitrogen and other contaminants from a hydrogen stream, in order to obtain purities of about 99.9% from the gas.
U.S. Pat. No. 6,746,515 B2 describes thermally-enhanced pressure swing adsorption (PSA) processes.
Although they are part of the prior art, none of the abovementioned references describes or suggests the present invention as herein disclosed and claimed.